Control of steam temperature



1952 J. D. KU'PPENHEIMER 2,615,435

CONTROL OF STEAM TEMPERATURE Filed Jan. 18, 1950 INVENTOR JOHN D. AUPPENHE/MER Fig.5 fl w -w ATTORNEY Patented Oct. 28, 1952 John D Kuppenheimer, Worcester, Mass., as-

signor to Riley Stoker Corporation, Worcester, Mass, a corporation of Massachusetts Application January 18, 1950, Serial No. 139,167

This invention relates to the control of steam temperature, and more particularly to an apparatus' for controllin the temperature of steam leaving a superheater.

It is one object of the invention to provide a simple and inexpensive apparatus whereby the temperature of steam leaving a superheaterv may be maintained at a desired value.

It is a further object of the invention to provide an apparatus for steam temperature control which will not contaminate the steam.

.' in the specification and covered by the claims appended hereto.

I Referring to the drawings illustrating one embodiment of the invention, and in which like reference numerals indicate like parts. Fig. 1 is a longitudinal section through the upper portion of a steam generator; Fig. 2 is an enlarged view of a portion of Fig. 1; Fig.3 is a section. taken on the line 33 of Fig. 2; and

Fig. 4 is an enlarged view of a portion of Fig. 2. The embodiment illustrated includes a steam generator comprising a horizontal elongated cylindrical steam-and-water drum l0, water tubes ll associated with the drum, a superheater' i2 to receive steam from the drum, a superheater outlet header I4, a combustion chamber IS, a gas out let duct l6, and gas-directing baffles l8. It will be understood that a suitable fuel will be burned in the" combustionchamber l5'to provide hot gases which will heat the various water tubes and generate steam therein. The gases will escape through the duct i6, and the steam will be released in the drum I0. Tubes I!) are arranged in a longitudinally extending row along the drum in to conduct steam therefrom to the superheater Within the upper portion of the drum there is provided a steam passage 2| having a bottom wall 22 and end walls 23 (onlyone being shown). The inlet ends of the tubes l9'c'ommunicate with the front portion of thispassage to receive steam therefrom. In entering the passage 2! from the lower portion of the drum, the steam is compelled to flow through moisture separating apparatus 25 located in the rear portion of the passage. Onelsuitable construction for the apparatus 25 iS'diSClOSGd in the prior patent to Kuhner No.

2,235,892, granted March 25, 1941. The bottom wall 22 is shaped to provide a trough 21 which lies in front of the separator 25 and extends lengthwise of the drum. A J- shaped pipe 28 extends downwardly from the trough 21 to provide a drainage trap, the lower end of this pipe having a disk 29 resting thereon to form a check valve, this disk being free to move vertically within a guiding cage 30.

6 Claims. (01.122479) g 2 o With the construction as so far described, the temperature of the superheated steam reaching the steam outlet header l4 will vary with changes in the demand for steam, changes in the typeiof 'fuel used, or from other causes. In order to minimize such variations in steam temperature I maintain a suitable control over the moisture content of the steam leaving the drum 10. If the steam temperature increases slightly I increase the moisture content and vice versa. For this purpose two parallel horizontal pipes 32 are mounted one above the other within the passage 2| and extend lengthwise of the drum. These pipes extend through the end walls 23 and they may be closed at one end, the other ends being joined and connected by a union 33 (Fig.3) to a pipe 34 extending through one end of the drum l0. Apipe 35 is connected to the outer endfof the pipe 34. The portions of the pipes 32 located within the chamber 2| are provided with orifices 31 and they are surrounded by porous material 38 which is preferably of a fibrous nature, such as stainless steel wool, glass wool, or the like.

The porous material 38 surrounding each pipe 32 is preferably of airfoil shape, and in the embodiment illustrated it is provided with a blunt or rounded leading edge facing the on-coming stream, convex lateral surfaces, and a relatively thin trailing edge. This shape as shown is symmetrical about a plane passing through the axis of the pi-pe'32 and extending parallel with-the general direction of flow of the steam as it travels from the separating-apparatus 25 to the tubes iii. For convenience in installation theporous material 38 is preferably pressed or otherwise formed into separate bats of appropriate length, each bat having one flat side which conforms with the plane of symmetry of the airfoil shape. In order to prevent the bats from turning about the pipes 32 each of these pipes carries two rows of studs 40 located on opposite sides of the pipeand lying in the plane of symmetry. The blunt leading edge of each airfoil is protected by a metal strip trolled by a valve 46 of the well-known diaphragm-operated type having a diaphragm chamber 41. This chamber 4'! is connected by a pipe 48 to a suitable relay 50 which is connected by a pipe 5| to a thermostatic, bulb 52 located in the superheater outlet header l4. Air or other fluid under pressure is supplied to the relay 50 through a pipe 54. This relay is of a'well-known ent-is: t t a 1." In combination-with an elongated cylindrical 3 type arranged tovary the pressure in the diaphragm chamber 41 iniaccordance with changes in the temperatureto'which the bulb 52 is subjected. Preferably a manually operable valve 55 is mounted in a by-pass line 56 around the valve The operation of the invention will now be apparent from the above disclosure. Steam will be generated in the water tubes H and released in the drum ID. The steam will then flow through the separator 25, which will remove *r'noisture therefrom, and thence forwardly past the porous material 38 and into the tubes I9 leading to the superheater i2 and the outlet header Hi. The

,by-pas's valve 55" will be Qclosed, and water will fl'o iv through the pipe 35 under the control of Ithe'diaphragm valve 48, into the pipes '32, and

through'th perforations 31 into the porous material '38. ,As the {steam flows over the convex lateral surfaces of the porous material" 38 the pressure of the ste m will be slightly reduced, f and some vof the water held by the material v38 will evaporate into the steam, somewhat increasing ,themoistur'e' contentof'the steam. So long as the temperature of the superheated steam reaching the outlet header it remains at the desired value, no adjustment of the valve 46 will take place. If however the steam temperature j increases even very slightly, the temperature responsive bulb 52 will respond to such increase and 'afiect' the relay so' that the pressure trans- .mitted through the' pipe 48 to the diaphragm .chamberfl l'will be varied as 'requiredto open the I' v'alv'eifi slightly. This will supply more water to the pipes 32 and to 'theporous material 38, more moisture will be evaporated from this material into: the steam, vthereby increasing the moisture content of'the steam entering the superheater J2, and the steam temperature at the outlet 'header I4 Will be restored to the desired value. Similarly,v if the steam temperaturebecome too low, the val vedfi will be.actuated to reduce the supply ofwater to the porousmaterial v38, the

Since the moisture is added to the steam bythe evaporation of, water supplied through the pipe 135, any dissolved or suspended f foreign matter .fcarried by this. water will be deposited in the porous material38,rather than injectedinto the steam to contaminate the same. ['Accumulations .dfsuchmatter may be removed from the material 38 by opening the'by-pass valve '55 for a brief interval tdprovide a, large momentaryfiow of water through the pipes '32, thereb flushing the jforeig'n matter out of the material'i38 and into the "trdugh 21, whence itWill escape through the trap 2'8 into the boiler water. During this operation the'boiler should preferably be relieved of all or most of'its'load. .Such fiushing'ofthe material 38 'i'willseldom be redu'iredunless the water supply contains considerable foreign matter.

- It will be rec'ognized'thattheinvention provides a new and'highly advantageous apparatus'whereby the temperatureof superheated steam may be accurately controlledi' drum having a longitudinal row of steam outlets therein and a passage for the flow of steam in a direction substantially perpendicularto the longitudinal axis of the drum to the outlets, a superheater connected to the outlets to receive steam therefrom, a pipe located within the passage and extending lengthwise of the drum, the pipe having orifices therein, a body of porous material enclosing the pipe and shaped as an airfoil so that the pressure of the steam flowing over the surfaces of the body will be slightly reduced, means to supply water to the pipe for discharge from .the orifices thereof into the porous material and evaporation by the steam, and means to increase the rate of water supply as the temperature of the steam leaving the superheaterjincreases and vice versa. p r

2. Apparatus .as set forth in claim 1, in which the body of porous materialfis provided with a blunt leading edge facing the o'n-coming steam and with a trailing edge which is relatively sharp compared with the leading edge.

3. Apparatus as set forth in claim ,2, in which the blunt leading edge is protected by'a'jmetal strip of arcuate crossrsection, and the sharp trailing edge is protected by a metal strip'of V cross-section.

4. Apparatus as set forth in claim 1, in which the body of porous material is formed of separate bats located on opposite sides of a plane passing through the axis of thenpipe and extending parallel with the general directionof'flow of the steam in the passage, the .body'being substantially symmetrical about the said plane. I

5. Apparatus as set forth in ;claim 4, inwh'ich the pipe carries two .rows of projecting studs located on opposite sides of the'pipe and lying-in the plane of symmetry.

6.. In combination with an elong-atedcyHndrical .drum havin a longitudinal row of steam outlets therein and-a passage for the fio'wof steam substantially perpendicular to the longitudinalfax is of the drum to the outlets, a superheaterconnected to the outlets .to receive steamitherefrom, a pipe located within .thepassage and extending lengthwise of the drum, the pipe having orifices .therein a .body of .porous material enclosing the pipe so that Ithelpres'sure of the steam Ifiowing over the surfaces, of the body will .be slightly reassumptions. CITED The following references are ,of record file of this patent:

UNITED STATES PATENTS Name 7 "Number Date I 1,003,792 Primrose f 'Sept. 1'9, 1911 .l,682,5.46 jBangert Aug.f.23, 1928 1,755,733 I-Iager etial. a Apr..'2 2,.19 1300,740 McD'ermot JApr. 11A, "1931 1,819,244 Jacobus ug. 18;"1931 "896,181 Lucke Feb. 7, 119,33

, FOREIGN PATENTS Number Country Date 672,'837 Germany Marglil, 1939 

